Transformer assembling method and apparatus



Nov. 12, 1940. s. qEvAr s' I 2,221,687

TRANSFORMER ASSEMBLING Margo]; AND APPARATUS Filed Aug. 23; 1939Invehto'r: Sidle 0. Evans,

' Hi: XXttcwwwey Patented Nov. 12,1940

PATENT OFFICE msnsroamza assnrmnmc m'zrnon Amp APPARATUS I Sidiey 0.1mm, Pittsfleld, m, assignor to Gen. eral Electric Company, acorporation of New- York- Application August 2a, 1939, Serial No.292,115 I h 3 Claims. -(c1. 242-4) My invention relates to methods andapparatus for assembling transformers, reactors, and other stationaryinduction apparatus and concerns particularly apparatus of thewound-strip-core type. 6 In United States Patents 2,160,588Granfleld'Electro-magnetic induction apparatus and methd of making the same, and2,160,589-Grah- 'fieldApparatus for makingstrip wound magneticcores-there are disclosed methods and apl0 paratus ,for applyingmagnetic cores of the wound-strip type to conductive winding structures.One of the steps in the Granfleld process involves the unwinding of acoil of magnetic strip into a larger loop, which larger loop is passedthrough the window-of a conductive winding in order that the strip maybe unwound from the original coil and simultaneously rewound around the.conductive-winding leg, it being important to avoid excessive str 0! themagnetic strip material. Excessive tortion of the larger loopmust'accordingly be avoided. In certain types of conductive-windingstructures; such as socalled two-group or three-legged conductivewindingstructures and winding structures hav--- ing more than two groups andmore than three legs, the space into which such a larger loop may bepassed while winding it around the center leg of the winding structuretends to become rather restricted so as to make it diflicult to pass thelarger loop around the center leg of the winding structure withoutexcessive distortion of the larger loop.

It is an object of my invention to provide arrangements for avoidingsuch distortion and to provide modifications. in the arrangement oi theaforesaid Graniield patents to'adapt Granflelds core-applying method totwo-unit three-legged winding structures and winding. structures havingmore than two units or more than three legs.

40 Other and further objects and advantages will become apparent as thedescription proceeds.

My invention may be understood more readily from the following detaileddescription when considered in connection with the accompanying drawingand those features oi. the invention which are believed to be novel andpatentable will be pointed out in the claims appended hereto.

In the drawing, Figure lis a diagram illustrating one step in theprocess of app y n a wound core to a conductive winding structure inaccordance with one embodiment of my invention.

Figure 2 is a diagram illustrating a more advanced step in the processrepresented in Figure 1. Figure 3 is a diagram representing-a still moreadvanced step in the same process, showing the beginning of theapplication of the strip to the center leg of a three-legged or two-unitconductive-winding structure. Figure 4 is a view partially insection. ofthe completed transformer illustrating the final step in the processrepresented in Figures 1 to 3 inclusive. Figure 5 is a diagramillustrating a step in the beginning of apro'cess constituting .anotherembodiment of my invention. Figure 6 is a diagram illustrating a moreadvanced step in the process represented in Fig- 10 ure 5, andillustrating also a form of machine which may be employed in carryingout the. process, and Figure 7 is a diagrammatic representation of amachine which may be employed in carrying out theprocessnof Figures 1 to4, inclu- 1 sive. Like reference characters are utilized throughout thedrawing to designate like parts.

My invention is concerned with the application of a hollow cylindrical,flatwise spirally wound core or magnetic strip material to a con- 20ductive-winding structure of the three legged or radial type in whichthere is more than one group of coils. Conductive windings of this typehave usually a center leg which is common to all of the groups of coilsand around which-the mag- 25 there are only two coil groups I! and."radiat- 35 ing from the center so that a three-legged wind ing structureresults consisting of the center leg Ii and the outer legs I and IE; butif additional coil groups were employed there would be so manyadditional outer legs radiating from a center leg, T

such as the leg Ii, which would include one side of each or the coilgroups. In the apparatus illustrated, taking the form of a transformer,each coil group consists of a pair of concentric windings It and ILonesurrounding the other, and 5 one being the primary winding and theotherheing the secondary winding. It will be under! 'stood, of course,that this method of assembly may be used equally well for conductivewind-r ings which are of the interleaved or pancake typ 50 It will beobserved also that the cross-sectional shapes oi the componentwindingsare so chosen that when the various coil groups are fitted-together, acenter. leg II is formed which is of a. shape tending substantially tofill a circular open- I- ing IS in the magnetic core so that the mean]The larger loop 2| is thereupon placed over the length of turn of corestill is as short as possible, with a resultant saving in steel. In thecase illustrated, theceuter leg H has a cruciform section.

A step in theprocess described in the Granfleld Patent 2,160,588involves the simultaneous unwinding of a coil of magnetic stripmaterial,

such as the coil ,20 in Figure 1, the rewindingof the material into alarger loop, such as the loop 2| in Figures 1 and 2, the larger loopbeing wound about the conductive winding leg in the arrangementdescribed by Granfleld. It will be observed, however, that in connectionwith a conductive winding, such as that shown in my drawing, it would bedifficult to pass a larger loop, such as the loop 2|, around the centerleg- .without distortion thereof owing to the restricted space providedby the winding windows 22 and 2t (Fig. 3') owing to the spacialrelationship betweeh. the center leg I and the outer less It and I5. Inorder to .avoid distortion of the larger loop 2|, and in order to permitthe conductive winding structure to be fully assembled with the centerleg completely taped and insulated before the application of the corestrip is begun, I increasethe number of steps in the process shown inthe Granfield patents,.but I divide the step of forming the larger looparound the conductive winding leg into-two steps. I first form thelarger loop, and after it has been formed, 1 rewind the materialfrom thelarger loop into a smaller loop around the center leg of the winding,

The complete process may be described more in detail as follows. As inthe arrangement de-\ scribed in the Granfield patent the actual processof application of the coil of strip to the conductivewinding structurebegins after a coil of strip 20 has been formed, which is in the shapeof a hollow cylinder composed of a plurality of turns of strip materialtightly wound flatwise spirally and having the exact shape and sizewhich the finished core I9 (Figure 4) is to have in thecompletely'asse'mbled apparatus. It will be under- 45 stood that thisinitial coil of strip 20 hasv been subjected to suitable heattreatment-so as to reduce its watt losses and magnetizing current,

to remove strains within and beyond the elastic limit and leave it witha permanent set, tending to retain it in the shape and size shown. Thecoil ofstrip 20 is unwound into a larger loop2l by drawing off thelength of strip from the outside turns of the coil 20 and bringing theend 20 of the strip backupon the next lower adjacent layer of strip, asillustrated in Figure l. The end of the strip 2% is preferably securedto the adjacent layer of strip in some suitable manner, 'as by spotwelding in order to prevent collapse of the larger loop, since the coil,aspreviously explained,

has apermanent set tending to return it to the diameter of thesuccessive turns in the coil 20. The originalcoil 20 and'the: largerloop 25 are rotated so as to transfer the material from the coil 20 tothe larger loop 2| and one will observe 5 that the turns are in the samesequence in the coil 20 and the larger loop 2i. If desired, a pair ofrollers 2s and 2e, biafsed toward each other so as to engage the stripfrictionally may be employed' for performing the unwinding and re- 70winding operation. It will be unde that suitable driving means, notshown, may be. con- 'nected to one or both of the rollers iii and 26.

After very nearly all of the material has been transferred to the largerloop 2 i the larger loop conductive winding structure 21, as,illustrated in Figure 3, or vice v'ersa,such a winding structure may beplacedwithin the larger.loop II, The inner end 28 of the strip ofmaterial in the larger loop 2| is allowed to loop around the center legI I of the conductive winding structure .21 and the direction ofrotation of the larger loop 2|- is then reversed so that the smallerloop 29 is permitted to wind around the center leg I I. The

' simultaneous rotation of the larger loop 2| andthe smaller loop 20causes the smaller loop 29 to circle around the leg building upprogressively with material from the innerl yer of the larger loop 2|passing to the outer! yer of the smaller loop 28. After all of thematerial in the larger loop 2| has been transferred to the smaller 'loop20, a core, such as the core i0, shown in Figurei'i, is formed. It, willbe understood, 0! 'course, that if the loop 2| is turned over 180 de- 20grees around one of its diameters, in going from the step representedin- Figure 2 to that repre-'- sented in Figure 3, it will be unnecessaryto reverse the direction of rotation. of the driving .rollers 25 and 26.Owing to the frictional engagement' between turns and with supportingstructure, not shown, there may be a tendency for the turns of thesmaller loop 20 not to return completely to the original shape anddiameter of the corresponding turn in the original coil. of strip, andit may be necessaryto overcome friction and tightenthe turns of strip inthe smaller loop 29 by hand or by means of col-. lapsing rollers, suchas the rollers 23 and 24, illustrated in Granfield Patent 2,160,589.This last step in the process, however, not being peculiar'to myinvention, need not be described or illustrated in'detail.

It will be understood that the conductive winding structure 2'! issupported in the position indicated by suitable means, not shown, andthat the process may be carried out with the axes of the loops 2| and 29eithervertical or horizontal, in which latter case the roller 25,together with guide rollers 30 and 8| would serve as a support for thestrip material in the loop 2|. The guide rollers 30 and 8|, togetherwith an additional guide roller efi serve to prevent collapse of thelarger loop 2|. 0n the other h nd, if 'the process is carried out withthe axes of he loops II and 29 vertical, a suitable table, not shown,will'be provided for the support ofthe loop 2|, asdisclosed in theGranijield Patent 2,160,589, and a slot in the table will be provided toreceive the conductive structure 21.

In connection with the assembly of apparatus r. of relatively largesize, the core material tends to become relatively heavy and thefriction of the strip 2| upon a supporting table may become ex oessivewhen the operation is performed with the axis of the loop 2| vertical.In order to overcome suchfriction and cause the loops 2| and 29 to berotated more easily.v and with equal peripheral velocities, the machinedisclosed in Figure '1 may be employed. In Figure 7 the apparatus isseen from the top. Planes through the edges of strip 7 in the *iargerand smaller loops 2i and 29 are horizontal. Relatively long cylindricalrollers.

88 are provided for the support of the strip material and guide rollersu are provided to guide the l rger. loop 2| upon the rollers .33 andprevent premature collapse of the larger loop 2|. The rollers 33 have,as indicated, horizontal. axes'and are radially disposed about thecenter leg ll,

to support the smaller loop 29 and extending sufficiently far outwardlyto support the larger loop 2|. Although the rollers 33 need becontinuous from the inner ends supporting the smaller loop 29 to theouter ends supporting the larger loop 2| they may conveniently becontinuous since in this manner assurance is provided that theperipheral velocities of the inner and outer legs will be the same andmaterial will be fed to the inner loop as fast as it is withdrawn fromthe outer loop. In connectionwith strip exceptionally sensitive tostrain, it will, of course, be advantageous to have the supportingrollers 33 at the positions 35, at the left-hand'side, continuous inorder that the portion of strip leaving the outer loop and approachingthe inner loop may have support. The rollers 33 are, of course,rotatably mounted upon suitable bearings which need not be shown, and,inorder to avoid manual labor, motor driving means, are provided forrotating all of the rollers 33, preferably at uniform speed, any desiredmechanical connection or gearing being used for this purpose.

For example, a driving motor 4| may be provided connected to the shaftof one of the rollers 33. For causing all the rollers to be drivenuniformly, there may be provided a ring gear 42 (shown fragmentarily)engaging pinions 43 forming extensions of the rollers 33.

Although I have shown in Figures 1 and 3, and have explained inconnection therewith a core applying arrangement in which the largerloop 2| entirelysurrounds the multl-unit conductive winding structure21, it will be understood that my invention is not limited thereto, andincludes any arrangements in which an intermediate step in the processconsists of encircling two or more of the legs of the conductive windingstructure, but not necessarily all of the legs of the winding structure,as shown in Figure 3. A subsequent step consists of rewinding the striparound the winding leg which is tobe'linked by the core in the finallyassembled apparatus. For example, as illustrated in Figure 5, theoriginal coil of strip 20 may be unwound and simultaneously rewound intoa larger loop 36 which does not surround all three of the legs ll, 14and I5 of the conductive winding structure 21, but instead surroundsonly the center leg H and one of the outer legs l5,

and passes through the winding window 23. In

this case, of course, as the coil of strip 29 is unwound it mustsimultaneously be rewound into the winding structure 21, and-a largerloop cannot subsequently be placed around the winding structure 21, asin Figure 3. As explained in connection with Figure 2, however, theouter end 24 of the strip is preferably fastened down to the adjacentlayer of strip and the rotation of the rollers 25 and 26, the coil 26,and the loop 36 are carried out until all of the material has beentransferred to the larger loop 36. Thereupon, the inner end 28 of thestrip is led around the center winding leg H and allowed to circletherearound forming the smaller loop 29. The direction of rotation ofthe driving rollers 25 and 26 and the larger loop 36 is then reversed,causing the ma-- terial from the inner layer of the larger loop 36 to betransferred to the outside of the smaller loop 29, simultaneouslyrotating the smaller loop 29 and causing it to build up to form thefinished core [9, as explained in connection with Figures 3 and 4.

If desired, a machine similar to that shown in Figure 7 may be employedfor causing the rotation of the larger and smaller loops 29 and 86 ofFigure 6 and supporting them during the winding process. In this case,however, two sets of rollers will be required since the loops 29 and 36are not concentric. For example, a set of rollers 31 and 38 may beprovided for supporting and rotating the smaller loop 29, the rollers 38serving also to support and rotate the larger loop 36, and a set ofrollers 39 may be provided -help-' ing to support and rotate the largerloop 36, all of the rollers preferably being driven at substantially thesame peripheral speed. As in Figure '7 the rollers 31, 38 and 39 havehorizontal axes of rotation. The gripping or driving rollers 25 and 26may either be retained or omitted, as desired in the arrangements ofboth Figure 6 or '7. I'f're-' tained, their peripheral speed ispreferably substantially. the same as that of the rollers 33, 31, 38 and39.

For removably supporting the winding structure 21 during rewinding andwinding operations, suitable adjustable clamps may be provided similarto the clamps 31 and 38 of Granfield Patent 2,160,589, for example. Asshown in Figure 5, the winding structure 21 rests between rubbercoveredrollers 40 of the lower clamp and similar rollers of an upper clamp,omitted from the drawingfor the sake of clarity. -A similar adjustablesupporting mechanism may be employed for the winding structure in theassembling machine of Figure '7, but is not shown in either Figure '7 or6 to avoid confusion in the drawing. It will be understood that thecore-supporting rollers 33, 31 and 38 are removable to'permit mountingand removing the winding structure 21.

Ihave herein shown and particularly described certain embodiments of myinvention and certain methods of operation embraced therein for thepurpose of explaining its principle and showing its application but itwill be obvious to those skilled in the art that many modifications andvariations are possible and I aim, therefore, to cover all suchmodifications and variations as fall within the scope of my inventionwhich is defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A method of assembling a wound strip, magnetic core with a two-groupconductive-winding structure having a center leg, which method comprisesthe steps of forming'a strip of magnetic material into a hollow cylinderof turns spirally wound flat-wise with a permanent set in sub--stantially the shape and size which the core is to have in the assembledapparatus, unwinding said cylinder into a larger loop with the turns inthe same sequence, bringing said larger loop en tirely around aconductive winding structure with which the core is to be assembled,looping the inner end of said larger loop of strip around the centerwinding leg to form a smaller loop encircling the said leg, and'rotatingthe loops of strip to transfer the strip to the smaller loop around thewinding leg.

2. A method of assembling a flatwise spirally wound hollow cylindricalcoil of magnetic strip with a two-group conductive-winding structurehaving a. center leg and a pair of winding windows, which methodcomprises the steps of unwinding the strip from the coil andsimultaneously rewinding it into a larger loop passing through one ofthe winding windows and surrounding two of the legs of the conductivewinding as well as the axis of the coil, rotating the '3 coil and loopto transfer the strip materialfrom the outside of the coil to the insideof the larger loop, until all of the strip material has been transferredto the larger loop, looping the inner end of the larger loop around thecenter leg of the conductive winding structure to form a smaller loopand reversing the direction of rotation of the larger loop to transferthe strip mate-- rial from the inside of the larger loop to the outsideof the smaller loop and thereby form a magnetic core surrounding saidcenter winding leg.

3. A method of assembling a flatwise spirally wound hollow cylindricalcoil of magnetic strip around a leg of a conductive winding having aplurality of legs and winding windows, which method comprises the stepsof bringing a rela-- tively large coil or loop of magnetic strip arounda plurality of the legs of the said conductive winding structureincluding said first-mentioned leg, looping the inner end of the largeloop around said leg of the conductive winding structure through twoadjacent winding windows to form a smaller loop and rotating the largeloop, together with the smaller loop, in such a direction as to transferthe strip material from the inside of the large loop to the outside ofthe smaller loop and thereby form a magnetic core surrounding said firstmentioned winding leg.

4. A machine for applying a wound-strip magnetic core to aconductive-winding structure consisting of two or more groups and havinga center leg, said machine comprising means for supporting such amulti-group winding structure with its center leg vertical, a pluralityof cylindrical rotatably mounted rollers with axes in a horizontal planeand radially disposed with respect to the position in which the centerleg is supported and of suflicient length to support both a loop ofmagnetic strip surrounding the center leg of the conductive windingstructure and a loop of such strip entirely surrounding the conductivewinding structure, vertical guides positioned to prevent collapse of thelarger loop upon the smaller, and means for rotating said rollers.

5. A machine for applying a wound-strip magnetic core to a conductivewin'ding structure consisting of two or more groups and having a centerleg, said machine comprising means for supporting such a multi-groupWinding structure with its center leg vertical, a pluralityofcylindrical rotatably mounted rollers with axes in a horiof such stripentirely surrounding the conductive winding structure.

6. A machine for applying a wound-strip magnetic core to a multi-groupconductive winding structure having a center leg, said machinecomprising means for supporting such a multi-group winding structurewith its center leg vertical, a set of cylindrical rotatably mountedrollers with axes in a horizontal plane radially disposed with respectto the position in which the center leg is supported and extendingrelatively close thereto, a set of rotatably mounted rollers with axesin the same horizontal plane radially disposed about a point off centerwith respect to the position in which the center leg is supported and ofsuflicient length to support a relatively large loop of magnetic stripsurrounding a plurality of the legs of the conductive winding structive,and means for rotating loops ofmagnetic strip material supported by saidrollers to transfer material from the inside of the large loop to theoutside of a smaller loop carried by the first set of rollers.

7. A machine for applying a wound-strip mag-v netic core to amulti-group conductive winding structure having a center leg, saidmachine comprising means for supporting such a multi-group windingstructure with its center leg vertical, a set of cylindrical rotatablymount-ed rollers with axes in a horizontal plane radially disposed withrespect to the position in which the center leg is supported andextending relatively close thereto,

a set of rotatably mounted rollers with axes in the same horizontalplane radially disposed about a point ofi center with respect to theposition in which the center leg is supported and of sufliclent lengthto support a loop of magnetic strip surrounding a plurality of the legsof the conductive winding structure, and means for rotating said rollerswith uniform peripheral velocities.

8. A machine for applying a wound-strip magnetic core to a multi-groupconductive winding structure consisting of a plurality of Winding legsincluding a center leg, said machine comprising means for supportingsuch a multi-group winding structure with its center leg vertical,cylindrical rotatably mounted rollers with axes in a horizontal plane,said rollers being so positioned in relation to the winding supportingmeans as to be adapted to support a loop of mag netic strip materialsurrounding only said center leg, and to. support a loop of suchmaterial surrounding a plurality of legs on the winding structureincluding said center leg, respectively, and

means for rotating said rollers with uniform peripheral velocities.

SIDLEY O. EVANS.

